How to sort Hashmap by key in Java

This tutorial shows you how to sort hashmap by key in java using java.util.TreeMap. Beside it also shows how to sort a hashmap in Ascending or Descending order by key or value using a custom Comparator and Java 8 Lambda expression.

Sorted HashMap By Key Example You sort a java.util.HashMap by putting all the entries in a java.util.TreeMap. It will be sorted automatically. Let’s look at the blow code snippet.